it is surprisingly economical, i got 33mpg out of it on the way back over 100 miles and i wasnt driving like a saint really. I Totaly agree on the tax laws, its almost criminal that my other halfs focus costs the same to tax as the 330.
As for the LPG, its deffo an avenue i'm looking to explore. All depends on what sort of free cash i have at the end of the year.
I'm hoping the warning light is a coil pack so will go out and test them tomorrow.